A reduction in reflection of light applied from external light sources such as fluorescent lamps and an enhancement in the visibility of image are required of an image display face in image display devices such as liquid crystal displays (LCDs) or cathode ray tube display devices (CRTs). To this end, it is common practice to reduce the reflection from the image display face in the image display device and thus to improve the visibility by providing an optical laminate (for example, an antireflection laminate) which has realized a lowered reflectance by covering the surface of a transparent object with a transparent film having a low refractive index.
The prevention of lowered contrast and lowered visibility caused by external light reflection or image reflection is required of image display devices, for example, cathode ray tube display devices (CRTs), plasma displays (PDPs), organic or inorganic electroluminescent displays (ELDs), field emission displays (FEDs), or liquid crystal displays (LCDs). Accordingly, it is common practice to provide an antireflection laminate on the outermost surface of an image display device from the viewpoint of reducing image reflection or reflectance using the principle of light scattering or the principle of optical interference.
Further, for example, from the viewpoint of contamination preventive properties of the display face of image display devices, it is common practice to provide an antistatic layer in the optical laminate. For example, Japanese Patent Laid-Open No. 94007/2004 proposes an antireflection optical laminate comprising an antistatic layer and a hard coat layer provided in that order smoothly on a surface of a light transparent base material.
In the antireflection laminate with a layer having a large refractive index difference stacked thereon, interface reflection and interference fringes often occur at a mutually superimposed layer interface. In particular, it has been pointed out that interference fringes occur at the interface of a light transparent base material and an antistatic layer resulting in lowered image visibility.
So far as the present inventors know, up to now, any optical laminate, which could have effectively prevented interface reflection and interference fringes by adopting an antistatic layer having a concavoconvex shape and specifying the concavoconvex shape by specific property values and, at the same time, the adhesion of interface between layers constituting the optical laminate could have been improved by adopting an antistatic layer having a concavoconvex surface, has not been proposed.